They work in farm country just as well as anywhere else. The difference is farmers aren't leaving their crops standing through the season. You plant corn or beans and leave them standing those deer will be all over it, whether in ag country or not. Like Milo said, they use it for cover just as much as for food.If you are in farm country why will the deer come to your corn and beans? In my mind it has to be a special draw of some kind.
A expert I am not by any means but this is what I've seen in the last 2 years.
When deer walk out of the neighbors brush and walk 200 yds. through a field of high quality horse hay non stop and go straight to my WT Inst. clover patch that tells me it's a special draw.
I've had excellent results with WT Inst. clover and Forage Oats the last 2 years and I see no reason to change. I had a very bad 2014 experience with another seed company planting so I'll never go back there. I got a grass that took over and smothered out 1/2 ac. of beets, turnips and radish. That seed company will go un-named.
In the future I will plant only clover and forage oats. I plant turnips and radishes because I love to eat them myself plus the deer eat the tops off in the winter.
Ask me in 5 years how it's working out.